Surface Oscillations in Overdense Plasmas Irradiated by Ultrashort Laser Pulses

The generation of electron surface oscillations in overdense plasmas irradiated at normal incidence by an intense laser pulse is investigated. Two-dimensional (2D) particle-in-cell simulations show a transition from a planar, electrostatic oscillation at $2\omega$, with $\omega$ the laser frequency, to a 2D electromagnetic oscillation at frequency $\omega$ and wavevector $k>\omega/c$. A new electron parametric instability, involving the decay of a 1D electrostatic oscillation into two surface waves, is introduced to explain the basic features of the 2D oscillations. This effect leads to the rippling of the plasma surface within a few laser cycles, and is likely to have a strong impact on laser interaction with solid targets.Comment: 9 pages (LaTeX, Revtex4), 4 GIF color figures, accepted for publication in Phys. Rev. Let

Multiple extraordinary optical transmission peaks from evanescent coupling in perforated metal plates surrounded by dielectrics

© 2010 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibitedWe study numerically and theoretically the optical transmission of nanostructured gold films embedded in dielectric claddings. We show how multiple transmission peaks appear as the claddings thickness increases. These transmission peaks come not only from surface plasmon polariton excitations but also from the excitation of Fabry-Perot modes sustained at the claddings, coupled through the metal, as long as a periodic pattern is milled in the metal film. We propose that this structure could be used as an ultracompact all-optical switch by surrounding the metal film with Kerr nonlinear dielectric layers. (C) 2010 Optical Society of AmericaWe thank the FCT (Fundacao para a Ciencia e Tecnologia) for funding of this research through the projects SFRH/BD/8278/2002 and PTDC/FIS/68419/2006.Ortuño Molinero, R.; García Meca, C.; Rodríguez Fortuño, FJ.; Martí Sendra, J.; Martínez Abietar, AJ. (2010). Multiple extraordinary optical transmission peaks from evanescent coupling in perforated metal plates surrounded by dielectrics. Optics Express. 18(8):7893-7898. https://doi.org/10.1364/OE.18.007893S78937898188Dragila, R., Luther-Davies, B., & Vukovic, S. (1985). High Transparency of Classically Opaque Metallic Films. Physical Review Letters, 55(10), 1117-1120. doi:10.1103/physrevlett.55.1117Ebbesen, T. W., Lezec, H. J., Ghaemi, H. F., Thio, T., & Wolff, P. A. (1998). Extraordinary optical transmission through sub-wavelength hole arrays. Nature, 391(6668), 667-669. doi:10.1038/35570Koerkamp, K. J. K., Enoch, S., Segerink, F. B., van Hulst, N. F., & Kuipers, L. (2004). Strong Influence of Hole Shape on Extraordinary Transmission through Periodic Arrays of Subwavelength Holes. Physical Review Letters, 92(18). doi:10.1103/physrevlett.92.183901Takakura, Y. (2001). Optical Resonance in a Narrow Slit in a Thick Metallic Screen. Physical Review Letters, 86(24), 5601-5603. doi:10.1103/physrevlett.86.5601Zhou, L., Wen, W., Chan, C. T., & Sheng, P. (2005). Electromagnetic-Wave Tunneling Through Negative-Permittivity Media with High Magnetic Fields. Physical Review Letters, 94(24). doi:10.1103/physrevlett.94.243905Lomakin, V., & Michielssen, E. (2005). Enhanced transmission through metallic plates perforated by arrays of subwavelength holes and sandwiched between dielectric slabs. Physical Review B, 71(23). doi:10.1103/physrevb.71.235117Rakić, A. D., Djurišić, A. B., Elazar, J. M., & Majewski, M. L. (1998). Optical properties of metallic films for vertical-cavity optoelectronic devices. Applied Optics, 37(22), 5271. doi:10.1364/ao.37.005271Genet, C., & Ebbesen, T. W. (2007). Light in tiny holes. Nature, 445(7123), 39-46. doi:10.1038/nature05350Ghaemi, H. F., Thio, T., Grupp, D. E., Ebbesen, T. W., & Lezec, H. J. (1998). Surface plasmons enhance optical transmission through subwavelength holes. Physical Review B, 58(11), 6779-6782. doi:10.1103/physrevb.58.6779Martínez, A., & Martí, J. (2005). Negative refraction in two-dimensional photonic crystals: Role of lattice orientation and interface termination. Physical Review B, 71(23). doi:10.1103/physrevb.71.235115Ruan, Z., & Qiu, M. (2006). Enhanced Transmission through Periodic Arrays of Subwavelength Holes: The Role of Localized Waveguide Resonances. Physical Review Letters, 96(23). doi:10.1103/physrevlett.96.233901Economou, E. N. (1969). Surface Plasmons in Thin Films. Physical Review, 182(2), 539-554. doi:10.1103/physrev.182.539Esembeson, B., Scimeca, M. L., Michinobu, T., Diederich, F., & Biaggio, I. (2008). A High-Optical Quality Supramolecular Assembly for Third-Order Integrated Nonlinear Optics. Advanced Materials, 20(23), 4584-4587. doi:10.1002/adma.200801552Spano, R., Daldosso, N., Cazzanelli, M., Ferraioli, L., Tartara, L., Yu, J., … Pavesi, L. (2009). Bound electronic and free carrier nonlinearities in Silicon nanocrystals at 1550nm. Optics Express, 17(5), 3941. doi:10.1364/oe.17.003941Dani, K. M., Ku, Z., Upadhya, P. C., Prasankumar, R. P., Brueck, S. R. J., & Taylor, A. J. (2009). Subpicosecond Optical Switching with a Negative Index Metamaterial. Nano Letters, 9(10), 3565-3569. doi:10.1021/nl901764

Theory of extraordinary optical transmission through subwavelength hole arrays

We present a fully three-dimensional theoretical study of the extraordinary transmission of light through subwavelength hole arrays in optically thick metal films. Good agreement is obtained with experimental data. An analytical minimal model is also developed, which conclusively shows that the enhancement of transmission is due to tunneling through surface plasmons formed on each metal-dielectric interfaces. Different regimes of tunneling (resonant through a ''surface plasmon molecule", or sequential through two isolated surface plasmons) are found depending on the geometrical parameters defining the system.Comment: 4 pages, 4 figure

On electromagnetic wave momentum transfer to an inhomogeneous plasma

Electromagnetic plane wave momentum transfer to an inhomogeneous plasma slab has been evaluated for an arbitrary reflecting and absorbing plasma density profile based on Euler's equation of motion but including a ponderomotive term. In the limit where the plasma density follows a step function, the Fresnel formulae for the coefficient of reflectivity have been obtained for both normal and oblique incidence (s- and p-polarization). For a smooth profile with a maximum density higher than the relevant critical density, the ponderomotive force induced pressure on the overdense plasma cannot be higher than 2 w0 (w0 is the electromagnetic energy density corresponding to the incident wave in a vacuum), and is independent of the wave swelling near the critical density. Also, for the case of oblique incidence, the analogues of the Abraham and Minkowski momenta have been calculated.Nous calculons le transfert d'impulsion d'une onde électromagnétique sur une couche de plasma inhomogène de profil de densité quelconque à l'aide de l'équation d'Euler incluant un terme de force pondéromotrice. Dans le cas limite où le profil de densité du plasma est une fonction en marche d'escalier, nous obtenons les formules de Fresnel en incidences normale et oblique (polarisation s et p). Pour un profil de densité régulier avec un maximum supérieur à la densité critique appropriée, la pression induite par la force pondéromotrice sur le plasma plus dense ne peut pas dépasser 2 w0 (w0 est la densité d'énergie électromagnétique de l'onde incidente dans le vide) et cette pression n'est pas modifiée par l'accroissement d'amplitude de l'onde près de la densité critique. Dans le cas d'une incidence oblique, on a aussi calculé les analogues des impulsions d'Abraham et de Minkowski

Laser plasma density profile modification by ponderomotive force

The plasma density profile modification due to the ponderomotive force is analysed by numerical treatment of a consistent system of hydrodynamical and Maxwell equations in a plane geometry. Reflectance temporal oscillations are proposed as a result of density profile oscillations at the cutoff.La modification du profil de la densité du plasma produite par la force pondéromotrice est analysée par un traitement numérique du système auto-cohérent des équations hydrodynamiques et des équations de Maxwell dans une géométrie plane. On prévoit des oscillations du pouvoir réflecteur en fonction du temps à cause des oscillations du profil de densité au cutoff

NONLINEAR SURFACE WAVES AND BISTABILITY OF DIELECTRIC PERMITTIVITY PROFILES SUSTAINED BY AN INTENSE RADIATION IN NONLINEAR LAYERS

No abstract availabl

Hydraulic redistribution by two semi-arid shrub species: implications for Sahelian agro-ecosystems

Hydraulic redistribution is the process of passive water movement from deeper moist soil to shallower dry soil layers using plant roots as conduits. Results from this study indicate that this phenomenon exists among two shrub species (Guiera senegalensis and Piliostigma reticulatum) that co-exist with annual food crops in Sahelian agro-ecosystems. Real-time measurements were conducted for soil water content, soil water potential and microclimate variables notably; air temperature, relative humidity, wind speed, precipitation and solar irradiance. Additionally, sap flow measurements were conducted in shrub roots using the thermal dissipation technique on intact and coppiced shrubs. Monthly predawn leaf water potential was measured using a portable pressure chamber. Soil water potential (Js) at the 20 cm depth declined significantly during the dry season with diel changes in Js of 0.6 to 1.1 MPa. These variations were attributed to passive water release from shrub roots resulting in overnight rewetting of drier upper soil layers. Sap flow measurements on tap and lateral shrub roots indicated daily reversals in the direction of flow. During the peak of the dry season, both positive (toward shrub) and negative (toward soil) flows were observed in lateral shrub roots with sap flow in the lateral roots frequently negative at night and rapidly becoming positive soon after sunrise. The negative sap flow at night in superficial lateral roots and the periodic positive flow in the descending tap roots were indicative of hydraulic redistribution. Hydraulic redistribution may be an important mechanism for drought stress avoidance while maintaining plant physiological functions in both shrubs and neighboring annuals in water-limited environments